This invention relates to a torque impulse delivering power tool with automatic power shut-off means.
In particular, the invention concerns a torque impulse delivering power tool comprising a drive unit with a rotor, power supply means connected to said drive unit, a power control means included in the power supply means, an output shaft, and a hydraulic impulse clutch coupling intermittently said drive unit rotor to said output shaft and comprising a drive member drivingly connected to said drive unit rotor.
In prior art impulse tools of the above type, as for example the one described in European Patent Application No. 0 292 752, the automatic shut-off means comprises a piston device which is exposed to the impulse generating hydraulic fluid pressure and which when activated releases a shut-off valve to, thereby, block the pressure air supply to the drive motor.
A problem inherent in a shut-off initiating mechanism of this known type is to seal off properly the piston device relative to the intermittently pressurized hydraulic fluid.
A primary object of the invention is to accomplish a torque impulse delivering power tool provided with an improved shut-off initiating mechanism by which the above described seal problem is avoided, i.e. a mechanism completely separated from and operationally independent of the hydraulic fluid
This is accomplished by the invention as it is defined in the claims.